1. Field of the Invention
This invention is directed to improved lubricant compositions comprising alkylated phenoxathin compounds alone as functionalized lubricant fluids or in combination with synthetic or mineral oil fluids, and to mineral or synthetic lubricant compositions containing said alkylated phenoxathin compounds as additives thereto.
2. Description of Related Art
Linear polyphenyl ether-thioethers and polyphenyl thioethers are known and have been used as lubricants in special applications. These materials suffer from very high cost due to difficult synthesis.
Polyphenyl ethers are known for their high temperature properties as noted in D. Klamen's "Lubricants and Related Products," Verlag Chemie, 1984, pp. 116-121, and references contained therein, and in product bulletin for OS-124 polyphenyl ether by Monsanto.
Mixed polyphenyl ether-thioethers are also known as noted in Monsanto bulletin for MCS-293. Phenoxathin is a heterocyclic aromatic structure which contains the ether oxygen structure found in diphenyl ether and the sulfur structure of thioethers. Phenoxathin, however, is a solid at temperatures up to 56.degree. C. and, therefore, does not possess physical properties attractive for lubricating fluids. Van Ess, U.S. Pat. No. 2,282,686 is directed to the use of certain "thioxins" such as phenoxathin as additives for hydrocarbon oils which are normally susceptible to oxidative deterioration. They are prepared in the presence of aluminum. These substances are added to lube oils, for example, in amount up to 10 wt%.
Smith, et al., U.S. Pat. No. 2,221,819, is directed to a method of making phenothioxine compounds and Smith et al., U.S. Pat. No. 2,277,833 is directed to higher alkyl substituted phenothioxins as novel compounds useful in plastic compositions. They are perpared in the presence of saturated bleaching earth catalyst.
Garces, U.S. Pat. No. 4,891,448 discloses the alkylation of polycyclic aromatics over natural zeolites such as mordenite, offretite and gmelinite.
None of the above noted prior art discloses the method of manufacture and use of alkylated phenoxathins as lubricant basestocks.
The present invention is directed to the alkylation of phenoxathins over zeolite catalysts which surprisingly results in a product which is predominantly or almost completely monoalkylated. Synthesized catalysts are preferred. Monoalkylated product comprises up to at least about 90% of the alkylation product in accordance with the present invention. In some instances the monoalkylation rate approaches 100%.
To the best of applicants' knowledge and belief the herein described alkylated phenoxathins have not been used previously as functional lubricant fluids or additives therefor.